Quantum projection noise: Population fluctuations in two-level systems

Itano, Wayne M.; Bergquist, J. C.; Bollinger, John J.; Gilligan, Jonathan M.; Heinzen, D. J.; Moore, F. L.; Raizen, Mark G.; Wineland, David J.

doi:10.1103/physreva.47.3554

Cited by 559 publications

(489 citation statements)

References 40 publications

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“…where ν is the atomic transition frequency, T is the Ramsey probe duration, and τ is the total measurement duration [33]. Local oscillator noise constrains clock stability by limiting T to some fraction η of the LO coherence time [34], which is often much shorter than the atomic coherence time.…”

Section: Analytic Estimates Of Clock Stabilitymentioning

confidence: 99%

Probing beyond the laser coherence time in optical clock comparisons

Hume

Leibrandt

2016

Phys. Rev. A

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We develop differential measurement protocols that circumvent the laser noise limit in the stability of optical clock comparisons by synchronous probing of two clocks using phase-locked local oscillators. This allows for probe times longer than the laser coherence time, avoids the Dick effect, and supports Heisenberg-limited measurement precision. We present protocols for such frequency comparisons and develop numerical simulations of the protocols with realistic noise sources. These methods provide a route to reduce frequency ratio measurement durations by more than an order of magnitude.

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Section: Analytic Estimates Of Clock Stabilitymentioning

confidence: 99%

Probing beyond the laser coherence time in optical clock comparisons

Hume

Leibrandt

2016

Phys. Rev. A

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“…We characterize the non-destructiveness of the measurement by the average number of photon recoils per atom m s imparted while achieving a measurement imprecision equal to the projection noise level of the atoms, m QP N s [40,41]. In our system, the atoms are not in a superposition of states, so there is no atomic projection noise.…”

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confidence: 99%

Strong coupling on a forbidden transition in strontium and nondestructive atom counting

Norcia

Thompson

2016

Phys. Rev. A

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We observe strong collective coupling between an optical cavity and the forbidden spin singlet to triplet optical transition 1 S0 to 3 P1 in an ensemble of 88 Sr. Despite the transition being 1000 times weaker than a typical dipole transition, we observe a well resolved vacuum Rabi splitting. We use the observed vacuum Rabi splitting to make non-destructive measurements of atomic population with the equivalent of projection-noise limited sensitivity and minimal heating (< 0.01 photon recoils/atom). This technique may be used to enhance the performance of optical lattice clocks by generating entangled states and reducing dead time.Two modes are strongly coupled when the frequency Ω at which they exchange excitations exceeds the rate of interaction with the environment. Strong coupling enables one to generate large amounts of entanglement [1, 2], achieve efficient quantum memories [3], cool the motion of atoms [4] and mesoscopic oscillators [5], and explore collective self-organization and synchronization phenomena such as superradiant lasing [6][7][8][9] and the Dicke phase transition [10,11].In this Letter, we observe strong coupling between an optical cavity and the collective excitation of up to N = 1.25 × 10 5 strontium atoms in a 1D optical lattice. The strong coupling is achieved using the forbidden electronic spin singlet to triplet optical transition 1 S 0 to 3 P 1 in 88 Sr. The excited state 3 P 1 couples to the environment via spontaneous emission at the relatively slow rate of γ = 2π × 7.5 kHz.Despite operating on a transition with 1000 times smaller squared matrix element than transitions typically used in optical cavity-QED experiments, we observe a highly-resolved splitting of the normal modes of the coupled atom-cavity system, known as a collective vacuum Rabi splitting [12,13]. This observation demonstrates that despite the relative feebleness of the transition, the tools of cavity-QED can now be applied to a system of extreme interest for quantum metrology [14]. Example technologies include optical lattice clocks [15][16][17] and ultra-narrow lasers [6][7][8][9], along with their associated broad range of potential applications such defining the second [14,18], quantum many-body simulations [19], measuring gravitational potentials [20] and gravity waves [21], and searches for physics beyond the standard model [22,23].One relevant application of this newly achieved regime is for state-selective, non-destructive counting of strontium atoms. Such counting has been used to generate highly spin-squeezed states [1,24] that surpass the standard quantum limit on phase estimation [25][26][27]. More simply, but quite importantly, non-destructive readout methods [28] can reduce the highly deleterious effects of local oscillator noise aliasing [29,30] in optical lattice clocks. Here, we utilize the observed vacuum Rabi splitting to non-destructively count atoms with the equivalent of sub-projection noise sensitivity. We verify that this sensitivity is achieved with as few as 0.01 photon recoils imparted to e...

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“…These proposals, therefore, naturally assume to use quantum logic spectroscopy (QLS) [18] by co-trapping optically accessible ions. From an experimental viewpoint, however, increase of number of ions is a pressing need in order to improve clock stability, which is limited by the quantum projection noise (QPN) [19]. Clock stability at QPN limit is given by σ y ≈ 1…”

Section: Ionmentioning

confidence: 99%

Optical clock sensitive to variations of the fine-structure constant based on theHo14+ion

2015

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We study the Ho 14+ ion as a candidate for extremely accurate and stable optical atomic clock which is sensitive to the time variation of the fine structure constant. We demonstrate that the proposed system has all desired features including relatively strong optical electric dipole and magnetic dipole transitions which can be used for cooling and detection. Zero quadrupole moments for the relevant states in the clock transition allows interrogating multiple ions to improve the clock stability.PACS numbers: 06.30. Ft, 06.20.Jr, 31.15.A, 32.30.Jc Theories unifying gravity with other fundamental interactions suggest a possibility for fundamental constants to vary in space or time (see, e.g. [1]). Searching for variation of the fundamental constants is an important way of testing these theories and finding new physics beyond standard model. Laboratory measurements limit the rate at which the fine structure constant α (α = e 2 /hc) varies in time to about 10 −17 per year [2,3]. On the other hand, the analysis of quasar absorption spectra shows that the fine structure constant may vary on astronomical scale along a certain direction in space forming the so called alpha-dipole [4]. Earth movement in the framework of the alpha-dipole (towards area of bigger alpha) 4f 6 5s 4f 5 s 2~4 0000 cm -1clock hfs-E1 λ~400 nm 6 H 5/2 (5) IonGround state Clock state Energy (cm −1 ) Er 14+ 4f 7 5s J = 4 4f 6 5s 2 J = 0 18555 Dy 10+ 4f 7 5p J = 3 4f 6 5p 2 J = 0 20835 Ho 14+ 4f 6 5s J = 0.5 4f 5 5s 2 J = 2.5 23800 would lead to the local time variation of α on the scale of 10 −19 per year [5]. To test the alpha-dipole hypothesis in terrestrial studies one needs a better accuracy in the laboratory measurements. The current best limit on the local time variation of α has been obtained by comparing Al + and Hg + optical clocks [2]. The result of this comparison limits time variation of alpha to (∂α/∂t)/α = (−1.6±2.3)×10 −17 yr −1 [2]), i.e. about two orders of magnitude improvement in accuracy is needed to test the alpha-dipole hypothesis. Current-best optical-clocks approach fractional uncertainty of ∼ 10 −18 [6][7][8]. However, the transitions used in these clocks are not sufficiently sensitive to the variation of α [9]. If α does change in time, the relative change δω/ω of the clock frequencies in any given period of time would be about an order of magnitude smaller than relative change in δα/α.It has been suggested in [10] to use highly-charged ions (HCI) as extremely accurate atomic clocks to probe possible variation of α. While HCIs are less sensitive to external perturbations due to their compact size, their sensitivity to variation of α is enhanced due to larger relativistic effects. In spite of the general trend of increasing energy intervals in HCIs, it is still possible to find clock transitions which are in optical range. This is due to electron energy level crossing while moving from the Modelung to the Coulomb level ordering with increasing

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Quantum projection noise: Population fluctuations in two-level systems

Cited by 559 publications

References 40 publications

Probing beyond the laser coherence time in optical clock comparisons

Probing beyond the laser coherence time in optical clock comparisons

Strong coupling on a forbidden transition in strontium and nondestructive atom counting

Optical clock sensitive to variations of the fine-structure constant based on theHo14+ion

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